In recent years, a capsule endoscope equipped with an imaging function and a radio communication function has appeared in the field of an endoscope. The capsule endoscope which is inserted from a mouth into a body of a subject for an observation (examination) has a configuration to travel according to their peristalsis to capture images of the inside of organs such as the esophagus, the stomach, the small intestine, and the like (inside of the body-cavity) by using the imaging function at a predetermine imaging rate during the observation period until it is naturally excreted from the body of the subject (human body).
During the observation period when the capsule endoscope travels inside the organs, image data captured by the capsule endoscope in the body-cavity is sequentially transmitted to the outside of the subject by a radio communication function such as a radio communication, and stored in a memory provided in a receiver placed outside of the subject. The subject carrying the receiver provided with the radio communication function and the memory function can freely move without having an inconvenience even during the observation period until the capsule endoscope, after being swallowed, is excreted.
In the case of receiving image data, the receiver generally has a plurality of antennas dispersed and arranged outside of the subject for receiving an image signal transmitted from the capsule endoscope, and selectively switches to one antenna having the strongest received strength to receive the image signal. Patent Document 1, for example, discloses a receiver which performs a reception switching among the plurality of antennas arranged outside of the subject, and detects the position of the capsule endoscope inside the subject as a source of image signal transmission, based on an electric field intensity each antenna receives.
In such a capsule endoscope system, it is a common practice that the image data stored in the memory of the receiver is transferred to a work station and the like after the capsule endoscope completes the series of imaging operation, and after-the-fact perusal of images are performed. However, since a doctor or the like has a strong demand for a real-time perusal of the captured images with respect to a site of interest, sites such as the esophagus, the stomach, and the like which can be diagnosed because the capsule endoscope passes such sites in a short time after the insertion, and the like, a system including a simple image display apparatus which displays, as a body-cavity image observation apparatus, images in real-time based on a radio signal transmitted from the capsule endoscope, has been proposed.
The conventional body-cavity image observation apparatus can be electrically connected to a receiver, and includes a compact display screen and a predetermined signal processor in its simplest configuration. With such a configuration, the body-cavity image observation apparatus can receive a signal to which a receiving process is performed in the receiver, and can display the images captured by the capsule endoscope on the small display screen after performing a predetermined process based on the received signal. In such a configuration, it is possible not only to observe the captured images in real-time, but also to check a reception condition of the receiver itself since the image received by the receiver is displayed on the display unit.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-19111